Alteration Development of the Simulated HLW Glass at High Temperature in Beishan Underground Water

The simulated HLW glass was found to be altered in Beishan underground water at high temperature in two different stages starting with slow leaching of the immobilized elements for a period followed by a sharp degradation of the glass matrix. Immersed at 150°C in Beishan underground water with glass-surface-area-to-solution-volume ratio of 6000 m-1, the glass was alterated rapidly with the sharp release of B, Na, Li, Cs, and Mo from the cold HLW glass after a stable period of 180 days. The glass was degraded up to 73.6% for the immersion period of 730 days resulting in the release of Mo and Cs up to 73.6% and 2.7% from the glass, respectively. With the alteration underway, new minerals were identified to be zeolite P, mordenite, nontronite, dickite, okonite, quartz, saponite, and tincalconite. However, at low temperature of 90°C, the glass was very stable with limited leaching of Na, B, and Li